Online syndicated content feeds, such as RSS feeds, are an increasingly popular mechanism for distributing information. As noted in part of a Wikipedia article under the heading “RSS (file format)”:                Web feeds are widely used by the weblog community to share the latest entries' headlines or their full text, and even attached multimedia files. (See podcasting, vodcasting, broadcasting, screencasting, Vloging, and MP3 blogs.) In mid 2000, use of RSS spread to many of the major news organizations, including Reuters, CNN, and the BBC. These providers allow other websites to incorporate their “syndicated” headline or headline-and-short-summary feeds under various usage agreements. RSS is now used for many purposes, including marketing, bug-reports, or any other activity involving periodic updates or publications.        A program known as a feed reader or aggregator can check a list of feeds on behalf of a user and display any updated articles that it finds. It is common to find web feeds on major websites and many smaller ones. Some websites let people choose between RSS or Atom formatted web feeds; others offer only RSS or only Atom.        RSS-aware programs are available for various operating systems (see list of news aggregators). Client-side readers and aggregators are typically constructed as standalone programs or extensions to existing programs such as web browsers. Browsers are moving toward integrated feed reader functions, such as Opera browser and Mozilla Firefox.        Web-based feed readers and news aggregators require no software installation and make the user's “feeds” available on any computer with Web access. Some aggregators combine existing web feeds into new feeds, e.g., taking all football related items from several sports feeds and providing a new football feed. There are also search engines for content published via web feeds like Feedster or Blogdigger. (from http://en.wikipedia.org/wiki/RSS_(protocol); links removed)        
However, it has been difficult or impossible to gather desired usage metrics for RSS and other feeds. Some metrics, such as a reliable count of the number of unique users, have been harder to gather for feeds than for other types of online information sources. Unlike feed usage, web site usage via browsers is regularly tracked and analyzed by commercially available web analytics services, which gather detailed data about web page usage, and to some extent about particular web site users. One leading web analytics provider is Omniture, Inc., of Orem, Utah, the owner of the present invention. Omniture provides web analytics technology under its well-known mark SiteCatalyst™.
Simply counting the number of times a feed file is accessed will not reliably reveal the number of subscribers, because a given subscriber's aggregator may poll the feed every ten minutes, while another subscriber's aggregator polls the feed once an hour. A dozen feed file accesses could mean that one person accessed the feed a dozen times, or that a dozen people each accessed the feed once, or some combination in between.
Identifying unique users of a feed allows one to state with confidence the number of readers. This circulation number may then be used to set advertising rates, to influence search engine rankings, to assert bragging rights within a community, and/or for other purposes. Moreover, distinguishing one feed subscriber from another also opens the door to personalized feeds, based on the demonstrated interest of a given subscriber, on the subscriber's stated preferences, and/or other criteria. Targeted advertising, customer profile building, poll throttling, and other subscriber-specific actions may also then be done. In short, significant benefits may follow from counting and/or individually identifying the subscribers to a given feed.
Suggestions have been made for ways to measure feed usage and/or count unique feed users. Several suggestions are discussed in documents submitted with the present application, but for convenience a brief introduction is also given here.
According to a “registered user only” approach, one or more security measures (passwords, usernames, encryption, and the like) are employed so that feeds are made available only to registered users. The number of registered users is then close to, and perhaps even exactly the same as, the number of subscribers. However, there is clear reluctance on the part of many people to require, or to submit to, a registration process for feeds.
According to a “unique URL” approach, each subscriber receives a feed which is associated with a URL containing a user-specific identifier. In some cases, the unique URL is generated and assigned when a user is redirected from the web page that offers feed access, to a page providing feed access. According to one proposal, the identifier is generated from a user's email address using a hash function. Using unique URL feeds makes it possible, for instance, to connect individual feed usage with user registration data. However, a unique URL may in some cases be syndicated to more than one person, or it may be manually given to the original subscriber's friend. In such cases, the number of subscribers may well be more than the number of unique URLs in use.
According to a “cookies” approach, each subscriber has a unique ID which is stored in a cookie data structure on the user's machine, and provided to the feed when a feed download is requested. Cookies can also be used in connection with unique URLs. However, a proponent of using cookies in podcast aggregators, Drew McLellan, notes that their use would complicate the podcasting model, would require support from major podcatchers, and has complications related to portability and privacy. In some cases, there may be one cookie per aggregator per device, even though all those aggregators and devices are used by a single person, so the number of subscribers would be over-counted.
According to a “web bug” approach, a uniquely-named one-pixel image is embedded in a feed's content, which contacts a server when it is loaded into a suitably-equipped browser. Email marketers and web analytics services use web bugs to track email and web site usage. However, use of such bugs in feeds is apparently not widely accepted. RSS feeds, for instance, typically contain little markup, so bloggers are more likely to notice—and remove—embedded web bugs.
According to an “IP address” approach, each feed reader IP address is treated as a unique user. The aggregator or news reader software sends the feed server its IP address when it checks the feed to see if new information is available. But IP addresses do not correspond one-to-one with subscribers. More than one person may use a single machine; each person using the machine sends the same IP address, so readership is under-counted. Moreover, it is not unusual for several machines to reside behind a firewall or gateway that does network address translation, so one IP address seen by a feed may easily correspond to multiple machines, and hence to multiple subscribers. It is also possible for a particular machine, such as a laptop or other portable computing device, or a machine served by an ISP that assigns addresses dynamically, to be assigned different IP addresses at different times. In these cases, counting IP addresses will over-count readership. In a variation of the IP address approach, the IP address is combined with other data, such as the type of feed and the type of software agent serving as aggregator, but the resulting user count is still only an approximation.
One approach suggests estimating RSS readership by dividing the number of hits to an RSS feed file by the “average polling interval”. However, a proponent of this approach, Amy Gahran, admits that average polling interval is not a readily available number. Critics of this proposal also point out that average polling interval depends heavily on the specific audience of a site and their computer usage habits. Using IP addresses generally as noted above is then suggested as an alternative to the average polling interval proposal.
Other related concepts will be known or apparent through other sources, not least of which are references such as those of record in the present patent application.